This application is a 371 of PCT/EP02/00921 filed Jan. 30, 2002.
This invention relates to a process for the antibacterial finishing of fibers or nonwovens, which exclusively or predominantly contain polyolefins or polyesters, to fibers or nonwovens finished by this process and to the use of a combination of glycerol monoesters and chitosan for the antibacterial finishing of fibers.
In the manufacture of sanitary articles, such as diapers or sanitary napkins, absorbent materials are used to absorb aqueous liquids. In order to prevent direct contact with the absorbent material during wear and to increase comfort, the absorbent material is wrapped in a thin water-permeable nonwoven. The nonwovens used for this purpose are normally made of synthetic fibers, such as polyolefin or polyester fibers, because fibers such as these are inexpensive to produce, exhibit good mechanical properties and, in the case of polyolefins, can be heat-bonded. However, untreated polyolefin or polyester fibers are not suitable for this particular application because, in view of their hydrophobic surface, they are not sufficiently permeable to aqueous liquids. Accordingly, the fiber surface has to be made hydrophilic by a corresponding finish. It is also desirable that the hydrophilic finish of the fibers should remain intact for as long as possible without any reduction in the permeability to water of the nonwoven. Accordingly, another problem arises out of the fact that the nonwovens used in sanitary articles are in direct contact with the skin and, hence, are exposed to significant bacterial contamination. Known spin finishes, which provide fibers the required hydrophilic finish, generally have no antibacterial activity so that, in unfavorable circumstances, for example in environments with high moisture levels, considerable bacterial growth can occur on the surface of the nonwoven. In cases of slight damage to the skin surface for example, this can lead to inflammation of the skin which should be avoided.
Hydrophilic finishing of fibers of the type under discussion is known from the prior art. U.S. Pat. No. 5,045,387, for example, describes a formulation for the hydrophilic finishing of polyolefin fibers which contains a mixture of an alkoxylated ricinoleic acid derivative, a hydrogenated ricinoleic acid derivative, a C18 fatty acid and a polyalkoxylated polymethyl siloxane. EP 395 099 A2 describes absorbent materials, more particularly tampons of rayon or polyester fibers, which are finished with glycerol monolaurate as a bacteriostatic toxin-inhibiting component. However, there is no reference to hydrophilic finishing of the fibers. WO 98/03716 proposes a combination of glycerol monoesters and alkyl polyglycosides for the hydrophilic finishing of fibers or nonwovens. However, nowhere in this document is there any reference to the problem of bacterial contamination.
The problem addressed by the present invention was to finish nonwovens in such a way that they would meet requirements in regard to the permanence of the hydrophilic finish and, in particular, would be capable of effectively suppressing the growth of harmful bacteria. The problem as stated is solved by the combination of antibacterial substances known per se with chitosan.